Power-Over-Ethernet (POE) is about twenty years old and has been mainstream for about six or seven years. Among other things, it is used to power security cameras. It replaces coaxial cable for this purpose. You could also use fiber optic cable for this purpose but the use of fiber optic cable brings numerous complexities and attendant problems.
In POE cable electrical power is transmitted over the same twisted pair wires as the data signals. Typical POE cable is Category 5e or Category 6 (also known as Cat 5e or Cat 6) twisted pair cable. Cat 5e and Cat 6 are open specifications set by the Telecommunications Industry Association (TIA), an offshoot of the Electronic Industries Alliance (EIA). Cat 5e cable is always 24 gauge AWG (American wire gauge). Cat 6 is 23 or 24 gauge AWG.
Presently the maximum length of a POE cable having these specifications is 100 meters. Once you go beyond that length you have to add a booster or an intermediate distribution frame (IDF) that is powered off the grid. Users would like to extend that 100 meter distance without having to incorporate boosters or IDF's, which just add complexity and cost. The TIA publishes a document TSB-184A D4 for Guidelines for Supporting Power Over Balanced Twisted-Pair Cabling. It is noted that this document only is applicable to mid-span power, which requires that a POE injector with a power supply be installed in a tamper-proof cabinet every 328 feet. This increases the cost of the installation and also adds potential points of failure to a video surveillance system. The end-to-end POE power supply approach of the present disclosure only requires that power be supplied on one end of the system.